﻿//FENGTODO
//无参数
public delegate void Callback();
//一个参数
public delegate void Callback<T>(T arg1);
//两个参数
public delegate void Callback<T, U>(T arg1, U arg2);
//三个参数
public delegate void Callback<T, U, V>(T arg1, U arg2, V arg3);
//四个
public delegate void Callback<T, U, V, Y>(T arg1, U arg2, V arg3,Y arg4);